// Copyright 2016 The Bazel Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package persistent.bazel.client;

import java.nio.charset.StandardCharsets;
import java.nio.file.Path;
import java.util.Map;
import java.util.SortedMap;

import com.google.common.hash.HashCode;
import com.google.common.hash.Hasher;
import com.google.common.hash.Hashing;

/**
 * Calculates the hash based on the files, which should be unchanged on disk for a worker to get
 * reused.
 */
public final class WorkerFilesHash {

  public static HashCode getCombinedHash(Path toolsRoot, SortedMap<Path, HashCode> hashedTools) {
    Hasher hasher = Hashing.sha256().newHasher();
    hashedTools.forEach((relPath, toolHash) -> {
      hasher.putString(toolsRoot.resolve(relPath).toString(), StandardCharsets.UTF_8);
      hasher.putBytes(toolHash.asBytes());
    });
    return hasher.hash();
  }
}
